1. Field of the Invention
This invention relates in general to a testing system for electronic assemblies, and more particularly, to a system which can reconfigure test paths of the electronic assemblies during testing periods.
2. Description of Related Art
Electronic devices and assemblies have become more complex during the past decade. Because of this increase in complexity, testing of these electronic assemblies has become more costly and more time consuming. Typical test times for assemblies are often three to five times the assembly time for assemblies of average complexity, and for the most complex assemblies, such as computer mother boards, test times of up to ten times the assembly time are not uncommon. Because of this increased cost in testing and increased time to test an assembly, advanced products cost more for consumers. Intricate computer chips, such as central processing units (CPUs), are more costly for end users because of the testing that must take place prior to shipping a unit for consumer use. This cost is passed directly on to the consumer.
The electronics industry has, by necessity, found methods to make this testing less costly and less time consuming. Automatic test equipment (ATE) is now normally constructed for production lines to standardize the tests for each device or assembly. ATE is also used to simulate actual conditions for the assembly, and can exercise the functions of the assembly under controlled conditions. Self-test features are also built-in to some devices, in order to give the user confidence that the electronics are working properly prior to actual use.
The ATE and self-test methods use the devices in the configurations that they will be used in their intended applications. This process may take several minutes or hours, depending on all of the functions that a self-test or ATE must test on the device before allowing the device to continue on to the next assembly level. If the testing is to be performed on a completed assembly or unit, the test can take several hours before a passable rating can be obtained, because of all of the functions and data paths that must be exercised.
These testing methods and testing machines are still rather costly and time consuming. These testing costs are still a significant percentage of the cost of the device to the manufacturer, as well as the consumer.
As electronics becomes more modularized and computer controlled, the electronics is divided by function and placed on printed circuit boards. The boards are designed to fit into a chassis or "card cage" that provides standardized inputs and outputs from each board. The chassis sometimes contains a backplane that is used for standardization of power and ground as well as data paths between board assemblies.
One skilled in the art will recognize that testing assemblies that are connected via a backplane is even more complicated than testing of individual modules. This complexity sometimes comes from the use of the backplane during the testing process, since the backplane can introduce timing errors, misconnections, and signal delays. Backplane testing is even more time consuming and expensive than assembly or device testing because the test must be "designed" by the test engineer. Further, the test is usually automated, requiring the engineer to write software programs and procedures to test the hardware connected to the backplane.
Because the hardware is usually designed to perform one specific purpose, the hardware cannot be reconfigured during a test to make the test easier or require less time to perform. This additional consideration makes testing of backplane connected assemblies more difficult, since the test engineer cannot design his test around his testing needs, but must design his test around the assemblies and backplane limitations. Because of this limitation, testing time is increased, and the cost of the end product to the consumer is higher.
It can be seen then that there is a need for a method of testing electronic devices and assemblies that is less costly. It can also be seen that there is a need for a method of testing electronic devices and assemblies that is less time consuming.